Objective(s): To determine the copy number and identity of the DAZ genes on the Y chromosomes of infertile patients.
Design: Prospective study.
Setting: University medical center.
Patient(s): One hundred and thirty-nine patients with male factor infertility.
Intervention(s): The separate genes were detected by polymerase chain reaction (PCR) digestion assays of sequence family variants in leukocyte DNA and by fluorescence in situ hybridization of interphase nuclei and chromatin fibers.
Main outcome measure(s): Number of DAZ genes present.
Result(s): One hundred twenty-nine patients had four genes, 6 patients had two genes, and 4 patients had none. Three patients had a deletion of the two proximal DAZ genes, and three were missing both distal genes. Semen analysis showed a less severe phenotype in patients with only two DAZ genes compared with patients missing all four genes.
Conclusion(s): In six patients, two different partial deletions were found that were not detected by PCR with conventional markers. One patient with an AZFb deletion appeared to also have a partial AZFc deletion that was not detected by routine PCR. Phenotypic differences between patients with different deletions suggest a dose effect of the DAZ genes.